It is well known to use a camera with photographic film to capture a photographic record of a scene. Films can be designed to capture a black and white (B&W) record, capture a full color (separate red, green and blue light sensitive records), or capture a special purpose light sensitive record (such as XRAYS, infrared, etc.).
It is also well known that multiple records of the same scene can be captured on photographic film, or any other light sensitive image capturing media, and then subsequently combined to achieve improved performance characteristics. Early experiments with color photography were done with color separations. Examples of commercial applications of combining color separations include the technicolor motion picture process (described in The History of Movie Photography by Brian Coe, pp. 133). This process featured the simultaneous capture of multiple images, through a single lens pointing to the scene, to produce color separations. These color separations are formed by passing the light from this single lens through a subsequent image beam splitter that divides the light into separate red, green, and blue components. Advantages of this system are that a full color image can be recorded on non-color discriminating (such as B&W) film. Disadvantages are a bulky camera resulting from the addition of a beam splitter and numerous alignment problems that occur both during the capture step and in the subsequent combining and printing of the color separations required to produce a full color image for display.
Furthermore, it is also well known that multiple images can be captured through multiple lenses. A well known example of multiple images captured simultaneously through multiple lenses is stereo photography wherein a three dimensional representation of the scene can be rendered on display from at least two images purposefully taken from slightly different angles of view in order to emulate, in the display, the slightly different views that are seen by humans. Examples of such a stereo camera include the Kodak Stereo Realist camera. An example of a simultaneous two image capture lens camera (a non-stereo application) is detailed in U.S. Pat. No. 2,921,509.
More recently, there have been various cameras introduced that feature multiple images captured, purposefully in a non-simultaneous manner, through multiple lenses. These systems, such as U.S. Pat. No. 5,424,792, are designed to produce a temporal sequence of events representation of a scene, frequently being using to capture various time segments of a motion action.
With both of the above-mentioned systems featuring multiple images captured through multiple lenses, combining images to produce improved performance characteristics is difficult owing to the fact that these images are captured through different lenses that have a slightly different view of the scene. The images arc not fully identical and therefore, in general, can not be optically combined without errors. Indeed it is these very view differences that provide the depth information required to render the three dimensional display for the above-mentioned stereo camera.
Combining images to produce improved performance characteristics is also well known. The above-mention technicolor process requires image combination to process a color image from three black and white color separation images. Furthermore, it is well known that multiple records of the same scene can be combined to produce an images with improved performance characteristics. An example of this is the combination of two photographs of the same scene which are sequentially optically printed on to the same projected area of photographic paper. As the scene information is correlated and the noise of photographic grain is not correlated between the two images, the resulting combined image from this sequential optical printing process is one with reduced photographic noise or grain. In general, the noise can be reduced, using this method, by a factor of the square root of the number of same scene images sequentially printed on to the same projected area of photographic paper.
Most recently a system has been described, Kokai Patent Application No. HEI 7[1995]-336590, wherein a plurality of images have been formed onto a single frame of photographic film. By making many smaller images, it is possible to reduce the focal length of the lens and therefore provide a thinner camera. Reducing the lens focal length to reduce both image and camera size is featured in Kodak Disc film cameras and subminiature cameras, such as those introduced by Minox Corporation in the late 1930's. The above mentioned Kokai discloses a camera wherein multiple images are "almost simultaneously exposed on film." It further discloses both the digital and optical combination of these multiple images to produce an image with improved performance characteristics. However, as these images are captured through multiple lenses, each pointing to the scene, these images will not have recorded the same view of the scene. The differences amongst these multiple images are particularly apparent with scenes that feature objects at different relative distances from the camera. As noted above, these differences, also known as parallax errors, provide the depth information required to render the three dimensional display for the above-mentioned stereo camera. In addition, almost simultaneously exposing images on film will, unfortunately, yield additional differences owing to scene object movement amongst the multiple images. Another problem with non-simultaneous exposure is that given its very short time duration, a single electronic strobe flash cannot be used to illuminate the scene. Therefore, in the above-mentioned teaching of optical printing of images from such a multiple lens camera, improved performance only results when the scene objects were at the same relative distant point from the camera and were not in motion.
Through improved camera design it is possible to overcome one of the above mentioned problems. It is well known that it is possible to simultaneously capture multiple images through multiple lenses each pointing to the scene and producing a separate record of the scene. This can be achieved, for example, by utilizing a multiple lens camera, such as that disclosed in U.S. Pat. No. 5,477,291 with a multiple lens shuttering means, such as that disclosed in U.S. Pat. No. 5,001,504. The above referenced two lens camera, U.S. Pat. No. 2,921,509, also features simultaneous multiple lens scene capture.
The above-mentioned parallax problem resulting from having simultaneously captured multiple images formed from multiple lenses, each pointing to the scene, remains a problem, particularly for scenes where the scene objects are not at the same distance from the camera. The above-mentioned Kokai teaches a method to allow combination of some of the multiple images in order to produce a digital image with improved performance characteristics. The method disclosed is one wherein the multiple images of the scene are selected (based on analyzing the digitized data) and digitally combined to produce a digital image with improved performance characteristics. In order to address the problem resulting from parallax, they further teach averaging (a form of combining) "after microimages that have a level of correlation that is below a reference level have been extracted." A problem with this method of combination is that where the scene objects are at different distances from the camera, the resulting parallax errors can result in many or even all of the additional microimages, available for combination, being extracted and not utilized, therefore leaving the resulting "reaveraged" (combined) image having little or even no improved performance characteristics.